1. Field of Invention
This invention relates to compositions for enhanced sanitation and oxidation of aqueous solutions, such as aquatic facilities, and methods for their use.
2. Background of the Technology
Aquatic facilities such as swimming pools, spas and fountains have become increasingly popular in private homes, hotels, fitness centers, and resorts. To ensure that the aquatic facilities can be enjoyed safely, the water must be treated to reduce or eliminate chemical oxygen demands (COD) and/or total organic carbon (TOC), and various pathogens such as bacteria, viruses, parasitic organisms and algae. When the COD and/or TOC increases in the water, the oxidation reduction potential of the water decreases and oxidizers are added to maintain a healthy level of oxidation reduction potential. A common oxidizer that is used in aquatic facilities is chlorine or bromine. However, when chlorine or bromine is present in the water above a certain level in the presence of COD and/or TOC, trihalomethanes (THM) and chloramines form in the water undesirably.
Common ingredients for treating water systems include various persulfate salts and persulfate donors such as potassium monopersulfate (PMPS), which is typically available in the form of a triple salt, (KHSO5)x.(KHSO4)y.(K2SO4)z (herein referred to as “PMPS triple salt”). However, PMPS typically contains persulfate salts, such as potassium persulfate (K2S2O8) as a by-product, are difficult to use because such persulfate salts can cause severe irritation to aquatic facility users (e.g., swimmers, bathers), in particular at concentrations above about 2 ppm. The strong oxidation potential of PMPS triple salt makes it effective for decreasing the concentration of COD. Typically, these chemicals are applied to the aquatic facility through a “shock treatment” whereby the facility is evacuated and the product is broadcast across the water surface. The facility users may not be allowed to come in contact with the treated water for a period of time after the treatment due to concerns for irritation. Typically facility users may not be allowed to come in contact with the treated water for about 15-30 minutes until the chemical has dissipated.
PMPS usually contains potassium persulfate (K2S2O8) as a result of being prepared using oleum. Persulfates such as K2S2O8 have a long half-life in aquatic facilities and are undesirable due to their irritant nature. As a result of the concerns for irritation resulting from accumulation of persulfate, PMPS can only be used in aquatic facilities in limited amounts, which typically do not exceed two pounds per 10,000 gallons of water per week.
While PMPS maintains the water quality in aquatic facilities reasonably well, it is not convenient to use because of the need to evacuate the facility during use and the fact that it can only be used in limited doses regardless of how heavily the facility is used. Furthermore, compounds found in aquatic and aqueous solutions may be resistant to oxidation by free halogen donors, such as chlorine and bromine, as well as commonly used oxidizers such as potassium monopersulfate, and alkali metal persulfates.
For example, when natural waters and wastewater are chlorinated, there is a residual oxidant formed, which remains stable at the breakpoint and in the presence of hypochlorite beyond the breakpoint. This residual oxidant responds to conventional methods of analysis in the same way monochloramine does. It can be shown that some organic amino nitrogen compounds form very stable organic N-chloramines that, unlike inorganic chloramines, do not decompose in the presence of excess hypochlorite”. (Drinking Water Criteria Document For Chloramines, Health and Ecological Criteria Division, Office of Science and Technology, Office of Water. Environmental Protection Agency, 1994).
To further illustrate, cyanuric acid, commonly used to stabilize chlorine donors such as trichloroisocyanuric acid, and dichloroisocyanuric acid can be placed in contact with hundreds of parts per million (PPM) of free chlorine as well as potassium monopersulfate, with no measurable affect on its concentration in water. Furthermore, the presence of transition metals such as copper or silver commonly used as an algae control agent, and applied in a concentration acceptable for use an algae control agent (typically between 0.2-0.5 ppm) with excess free halogen and potassium monopersulfate has no significant affect on the concentration of the oxidation resistant organic compounds like cyanuric acid.
Furthermore, with the accumulation of organic contaminants in the aqueous solution, the Oxidation Reduction Potential (ORP) is reduced unless the concentration of free halogen donor increases. When the concentration of free chlorine rises, the potential for formation of volatile trihalomethanes and chloramines increases (FIGS. 2 and 3). With a reduction in ORP, the rate of inactivation of microbiological organisms is reduced, and the potential for transfer of the organisms through the water from mammal to mammal increases. With application of the compositions and methods of the disclosed invention, the organic contaminants are rapidly oxidized, thereby allowing the ORP to be sustained or even increased with the same concentration of free halogen in the aqueous solution. Increases in ORP are correlated with an increased rate of inactivation of microbiological organisms.
Further still, many microbiological organisms such as parasitic organisms exemplified by cryptosporidium are very resistant to inactivation by free halogen donors due to the oxidation resistant compound (phospholipids and proteins) making up the environmentally protective membranes, in this case the outer oocyst. Inactivation or destruction of algae blooms requires high levels of free halogen with extended contact time due to the protective cellulose membrane of the algae.
While various oxidizer systems have been developed and explored for destruction of TOC, i.e., organics in ground water etc, there is a need for compositions and methods for applying such compositions to increase the rate of inactivation of microbiological organisms, in particular, oxidation resistant organisms such as parasitic organisms including cryptosporidium. There is also a need for compositions and methods for applying such compositions to increase the rate of inactivation of oxidation of oxidation resistant compounds in aqueous solution, more specifically aquatic facilities and drinking water.
Furthermore, there is a need for compositions and methods that are effective to facilitate quick recovery of an aquatic facility contaminated by oxidation resistant compounds as well as from the release of microbiological organisms derived from bodily discharge (i.e. fecal release, vomit, blood etc.), in particular those that exhibit resistance to inactivation from traditional free halogen donors and standard oxidizers such as potassium monopersulfate and persulfates. Further still, there exist a need for compositions and methods of applying said compositions to increase the rate of inactivation and oxidation in aqueous systems contaminated with organic compounds.
The present invention addresses these needs by providing compositions and methods for increasing the rate of inactivation of microbiological organisms and oxidation of oxidation resistant compounds in an aquatic facility, as detailed herein below.